1. Technical Field
This invention relates to a monoclonal antibody in relation to drug-resistant cancers and production thereof. More particularly, the present invention relates to the monoclonal antibody, a hybridoma which produces the same and a process for producing the monoclonal antibody.
It has heretofore been observed that cancer cells which are resistant to an antitumor agent selectively appear upon treatment of the cancer by chemotherapy, which poses a serious problem in the art. It may be an approach to overcoming the problem of drug-resistance to increase the dosage of the antitumor agent. However, increase of dosage will give unnecessary pains to patients through the side effects of disorders to normal cells. Another approach to overcoming the problem of drug-resistance may be to use several types of antitumor agents in combination, but this approach can be accompanied by a problem of what is called pleiotropic drug-resistance, thus bringing about little effect in many cases.
Accordingly, for the purpose of overcoming such drug-resistance of cancer cells, it is an important task to establish a drug or a method which has little side effects, high selectivity and effectiveness against cancer cells exhibiting pleiotropic drug resistance.
2. Prior Art
A monoclonal antibody which has selectivity to cancer cells having pleiotropic drug-resistance has been already prepared [J. Clin. Oncology, vol. 3, p. 311.about.315 (1985)]. It is a monoclonal antibody which is reactive with glycoproteins having molecular weights of 170,000 to 180,000 daltons which appear specifically on the cell membrane of a cancer cell exhibiting pleiotropic drug-resistance. However, the resistant cell line used in preparation of this monoclonal antibody is not derived from human but from Chinese hamster, and also nothing is reported about sensitivity of the drug-resistant cancer cells to the drug when use is made of this monoclonal antibody.
Therefore, nobody in the art would believe that the monoclonal antibody according to this prior art can be used in selective treatment of human drug-resistant cancer cells.